Reverse link power controlled repeater

ABSTRACT

The invention provides a mechanism for automatically setting reverse link gain or power for a repeater ( 120 ) used in a communication system ( 100 ) through the use of the reverse link power control of a built-in wireless communications device. By embedding a wireless communication device ( 430, 630, 700 ) inside the repeater and injecting reverse link signals of the embedded device into the reverse link of the repeater ( 124 A,  124 B), the gain of the repeater is maintained relatively constant. The embedded WCD can also be activated on a periodic basis to make calls and utilize reverse link power-control to calibrate or re-calibrate the gain of the repeater, making it a power-controlled repeater.

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit of U.S. Provisional PatentApplication Serial No. 60/331,943, filed Nov. 20, 2001, pending, whichapplication is incorporated herein by reference in its entirety.

BACKGROUND

[0002] I. Field of the Invention

[0003] The present invention relates generally to wireless communicationsystems, and more specifically, to a repeater for use in wirelesscommunication systems having an embedded wireless communication devicecapable of interacting with base stations communicating with and throughthe repeater to affect control of repeater gain and output power.

[0004] II. Related Art

[0005] Wireless communication systems have developed a great deal inrecent years and enjoy widespread use. There are presently manydifferent types of wireless communication systems in use, includingCellular and Personal Communications Service (PCS) systems. Examples ofknown cellular systems include the cellular Analog Advanced Mobile PhoneSystem (AMPS), and digital cellular systems based on Code DivisionMultiple Access (CDMA), Time Division Multiple Access (TDMA), the GlobalSystem for Mobile access (GSM) variation of TDMA, and newer hybriddigital communication systems using both TDMA and CDMA technologies.

[0006] The use of CDMA techniques in a multiple access communicationsystem is disclosed in U.S. Pat. No. 4,901,307, entitled “SpreadSpectrum Multiple Access Communication System Using Satellite OrTerrestrial Repeaters” and U.S. Pat. No. 5,103,459, entitled “System AndMethod For Generating Signal Waveforms In A CDMA Cellular TelephoneSystem,” both of which are assigned to the assignee of the presentinvention and are incorporated herein by reference.

[0007] The method for providing CDMA mobile communications wasstandardized in the United States by the Telecommunications IndustryAssociation/Electronic Industries Association in TIA/EIA/IS-95-Aentitled “Mobile Station-Base Station Compatibility Standard forDual-Mode Wideband Spread Spectrum Cellular System,” referred to hereinas IS-95. Combined AMPS & CDMA systems are described in TIA/EIA StandardIS-98. Other communications systems are described in the IMT-2000/UM, orInternational Mobile Telecommunications System 2000/Universal MobileTelecommunications System, standards covering what are referred to aswideband CDMA (WCDMA), cdma2000 (such as CDMA2000 1× or 3× standards,for example) or TD-SCDMA.

[0008] In wireless communication systems mobile stations or userterminals receive signals from fixed position base stations (alsoreferred to as cell cites or cells) that support communication links orservice within particular geographic regions adjacent to or surroundingthe base stations. In order to aid in providing coverage, each cell isoften sub-divided into multiple sectors, each corresponding to a smallerservice area or geographic region. An array or series of base stationsplaced adjacent to each other form a communication system capable ofservicing a number of system users, over a larger region.

[0009] Unfortunately, as extensive as the total coverage areas of manywireless systems appear to be, providing service or coverage to manymobile stations is not without difficulties. The deployment orpositioning of base stations within a system may leave “gaps” or “holes”in the coverage area. That is, the arrangement of the base stations,which can be dictated by various known system design criteria,economics, convenience, or local zoning restrictions, does not allow thesignal coverage of some base stations to reach certain areas that areadjacent to or even surrounded by a group of base stations. In addition,obstructions from geological features or man-made structures, may simplyblock signals in certain areas. Base stations may also be considered tooexpensive to place in lower populated or more rural areas, leaving largeareas simply uncovered. Of course, any un-covered area or region meanslost revenues for communication system operators or service providers.

[0010] Repeaters can provide a cost-effective way for carriers andservice providers to fill holes in the coverage area or to augment thearea of coverage. For example, rather than install a more expensive andcomplicated base station, a repeater can be used to extend the reach ofexisting base stations. Therefore, a carrier can achieve hole fillingand otherwise augment the area of coverage for a given sector to providecapacity in an area that was previously not covered. One mark of a holefilling application is that the area is generally surrounded bycoverage, often with the very sector that is also in communication withthe repeater. Augmenting, or moving, the coverage area of a cell orsector effectively shifts the location or the shape of the coverage areafrom a sector. An example of this type of application might be toprovide highway coverage. Assuming that two sectors cover a highwayadjacent to a base station, the use of a repeater might be considered inorder to provide coverage to an area beyond that immediately ‘visible’or reached by signals from the base station location. Especially, for amore rural location.

[0011] The use of repeater technology is described in U.S. Pat. No.6,108,364, entitled “Time Division Duplex Repeater for Use in a CDMASystem”, and the use of repeaters for obtaining signal diversity in viewof urban canyons is described in U.S. Pat. No. 5,991,345, entitled“Method and Apparatus for Diversity Enhancement Using Pseudo-MultipathSignals”, both of which are incorporated herein by reference.

[0012] However, the use of repeaters is not itself without problems incertain situations. As will be discussed further below, a repeater isnot a noise-less device and will contribute thermal noise into the basestation sector acting as the communication link, referred to as addingto the noise floor of the base station. The use of repeaters is furtherhindered by environmental factors causing fluctuations in repeater gain,and in the thermal noise contributions by the repeater at the basestation. More specifically, the gain provided by a repeater is affectedby factors such as: daily temperature variations (±6 dB); seasonaltemperature variations (typically ±3 dB); attenuation caused by foliageor foliage changes during spring and summer; or new obstacles beingerected along the base station-to-repeater path.

[0013] The phenomena stated above will result in fluctuations in thetotal amount of thermal noise at the base station, adversely affectingcoverage as well as service in both the base station and repeatercoverage areas. It can be seen that it is desirable to keep the gain ofthe repeater a constant. Therefore, it is desirable to have the abilityto detect and quantify a change, and restore the gain of the repeaterback to a pre-determined level.

[0014] What is needed is a new apparatus or technique to manipulate thepower output of a repeater in such a manner that it can enhance coveragewithout adding undesirable noise to a communication system. This shouldbe accomplished with a minimum of complexity and maximum ease of use.The present invention satisfies that need.

SUMMARY

[0015] The invention provides a mechanism for automatically setting areverse link operating point for a repeater used in a communicationsystem through the use of the reverse link power control of a built-inwireless device, for example a spread spectrum phone using CDMA or WCDMAstandards protocols. By embedding a wireless communication device (WCD)inside the repeater and injecting the reverse link of the embedded WCDinto the reverse link of the repeater, the gain of the repeater ismaintained relatively constant. The embedded WCD can also be activatedon a periodic basis to make calls and utilize reverse link power-controlto calibrate or re-calibrate the gain of the repeater. Therefore, therepeater becomes a power-controlled repeater.

[0016] The invention can be realized using a method or apparatus tocontrol output power for a repeater communicating with one or more basestations and remote stations in a wireless communication system, byadjusting the gain of amplification stages or elements used within therepeater. This invention also controls noise pushed to a donor basestation communicating with the repeater and one or more remote stations.

[0017] In one embodiment, the method comprises coupling or transferringa pre-selected portion of a donor base station communication signalintended for remote stations to an embedded wireless communicationdevice within the repeater, and establishing a communication linkbetween the wireless communication device and donor base station inresponse to receiving the pre-selected portion. This is accomplished bytransmitting a return link signal over a return signal pathsubstantially co-extensive with remote station communication signalsbeing transferred to the base station, then receiving power adjustmentinformation from the donor base station and generating at least onepower control signal for adjusting output transmission power. The returnlink gain of the repeater is adjusted in response to the power controlsignal.

[0018] In further aspects, a communication signal is received from thedonor base station which is to be transferred to remote stations, whilecommunication signals are received from one or more remote stations tobe transferred to the base station along a predetermined signal path.Typically, the communication signals are selected from the group ofCDMA, WCDMA, TDMA, TD-SCDMA, and GSM (including GPRS and EDGE) typecommunication signals. The pre-selected signal portion is processed inthe wireless communication device to establish a forward communicationlink, which includes generating a reverse link communication signal fortransfer to the donor base station. The reverse link signal istransferred along with the signals received from remote stations alongthe predetermined signal path to the donor base station. A communicationsignal from the donor base station directed to the wirelesscommunication device is received and a power control signal, such as anautomatic gain control signal, or command is generated in response toinformation in that signal. The repeater adjusts the return link gainbased on that power control signal or command.

[0019] Further aspects of the invention comprise transferring amplifiedremote station communication signals and received donor base stationcommunication signals through a first duplexor; power coupling apre-selected portion of a donor base station communication signal to thewireless communication device, which may include attenuating the signalby a pre-selected amount in some embodiments; and transferring amplifieddonor base station communication signals and received remote stationcommunication signals through a second duplexor. The return link signaloutput by the wireless communication device is combined with remotestation communication signals, and may also be attenuated in someembodiments before being combined.

[0020] The method can further comprise periodically establishing acommunication link between the wireless communication device and donorbase station, and generating at least one power control signal based oninformation related to signal power determined during a duration of thecommunication link. This feature is especially useful when initiallysetting up a repeater, since the repeater can effectively “call in” tothe base station and establish an appropriate power level without manualintervention.

[0021] Apparatus for controlling the output power for a repeatercommunicating with one or more donor base stations and remote stationsin a wireless communication system, comprises means for coupling ortransferring a pre-selected portion of a donor base stationcommunication signal intended for remote stations to an embeddedwireless communication device within the repeater, and means forestablishing a communication link between the wireless communicationdevice and donor base station in response to the pre-selected portion bytransmitting a return link signal over a return signal path shared withremote station communication signals being transferred to the basestation. Also, included is means for receiving power adjustmentinformation from the donor base station and generating at least onepower control signal for adjusting the output transmission power, andmeans for adjusting the return link gain of the repeater based on thatpower control signal.

[0022] The apparatus can further comprise means for receiving variouscommunication signals from a donor base station or remote stations,along with means for amplifying these signals and retransmitting them.The signals are transferred through duplexors to amplification stages.Means are provided for processing the pre-selected portion to establisha forward communication link, and for generating a reverse linkcommunication signal in the wireless communication device. The apparatustransfers the reverse link communication signal from the wirelesscommunication device along with signals received from covered remotestations along a shared signal path to the base station. In addition,means are provided for receiving a communication signal from the basestation directed to the wireless communication device and for generatinga power control signal. The power control signal may be detected usingmeans for detecting in the repeater, and the return link gain thenadjusted using means for adjusting the gain, based on the detected powercontrol signal.

[0023] Signals input to or output from the wireless communicationsdevice may be processed by one or more means for attenuating beforetransfer into or from the wireless communication device, as desired. Aresulting attenuated return link signal output from the wirelesscommunication device is combined with remote station communicationsignals. The attenuation before transfer into or from the wirelesscommunication device is typically only necessary in the case of using astandard production wireless communications device, if a custom devicewas designed for this application, the attenuation could be avoided.

[0024] The apparatus further comprises means for periodicallyestablishing a communication link between the wireless communicationdevice and donor base station, so that at least one power control signalis generated based on information related to signal power determinedduring a duration of the communication link.

[0025] In some embodiments, the communication signal from the donor basestation has a first frequency, and communication signals from one ormore remote stations have a second frequency different from the first.

[0026] In still further embodiments, more than one repeater is used,with one communicating directly with a base station and the otherscommunicating with either the first as a series of remote stations, orin a series one to the other and then to the first repeater.

BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The features, objects, and advantages of the present inventionwill become more apparent from the detailed description set forth belowwhen taken in conjunction with the drawings in which like referencecharacters identify the same or functionally similar elementsthroughout. In addition, the left-most digit of the reference numberrefers to the figure in which the reference number first appears in theaccompanying drawings.

[0028]FIG. 1 illustrates a typical wireless communications system usingseveral base stations and repeaters;

[0029]FIG. 2 illustrates a simplified high-level view of a repeaterdesign;

[0030]FIG. 3 illustrates a model of equivalent functions of therepeaters in FIG. 1;

[0031]FIG. 4 illustrates a high-level repeater design using theinvention;

[0032]FIG. 5 illustrates another high-level repeater design using theinvention;

[0033]FIG. 6 illustrates one type of embedded wireless communicationdevice;

[0034]FIG. 7 illustrates another type of embedded wireless communicationdevice;

[0035]FIG. 8 illustrates steps in deploying and operating apower-controlled repeater;

[0036]FIG. 9 illustrates an alternative use of multiple power-controlledrepeaters to provide coverage for various regions; and

[0037]FIG. 10 illustrates a graphical representation of alpha versusgamma values for different push rates;

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

[0038] I. Introduction

[0039] The present invention is a method and apparatus for controllingthe gain and the transmission power of a repeater used in a wirelesscommunication system by embedding a wireless communication devicecircuit within the repeater. The wireless communication device is powercontrolled or adjusted by base stations with which it communicates overa communication link held in common with repeater return linkcommunication signals. One or more signals or commands generated by thewireless device interact with the repeater to cause the repeater to begain and thus power controlled. As would be apparent to one skilled inthe relevant art, the concept of the present invention can be applied tomany types of communications systems where power control is used andthere is a desire to reduce signal interference or degradation.

[0040] Embodiments of the invention are discussed in detail below. Whilespecific steps, configurations and arrangements are discussed, it shouldbe understood that this is done for illustrative purposes only. It wouldbe apparent to one of skill in the art that the invention may beimplemented in many different embodiments of hardware, software,firmware, and/or the elements illustrated in the figures, and that othersteps, configurations and arrangements can be used without departingfrom the spirit and scope of the present invention.

[0041] Before describing embodiments of the invention in detail, it ishelpful to describe an example environment in which they may be usefullyimplemented. The present invention is particularly useful in mobilecommunication system environments. FIG. 1 illustrates such anenvironment.

[0042] II. Exemplary Operational Environment

[0043]FIG. 1 is a diagram of a typical wireless communication system100, such as a cellular telephone system. Wireless communication system(WCS) 100, uses one or more control stations 102, sometimes referred toas base station controllers (BSC), and a plurality of base stations104A, 104B, and 104C, sometimes referred to as base station transceiversystem (BTS). Base stations 104A-104C communicate with remote stationsor wireless communication devices (WCD) 106A-106C, respectively, thatare within service areas 108A-108C of base stations 104A-104C,respectively. That is, in this case, base station 104A communicates withremote station 106A within service area 108A, base station 104B withremote station 106B within service area 108B, and base station 104C withremote station 106C within service area 108C.

[0044] Base stations transmit information in the form of wirelesssignals to user terminals across forward links or forward linkcommunication channels, and remote stations transmit information overreverse links or reverse link communication channels. Although FIG. 1illustrates three base stations 104A-104C, other numbers of theseelements may employed to achieve a desired communications capacity andgeographic scope, as would be known. While fixed base stations aredescribed, it is to be appreciated that in some applications portablebase stations may be used, or even stations positioned on movableplatforms such on trains, barges, or trucks, as desired.

[0045] Control station 102 may be connected to other control stations102, central systems control stations (not shown) for the communicationsystem 100, or other connected systems communication systems such as apublic switched telephone network (PSTN) or the Internet. Thus, a systemuser at remote station 106 is provided with access to othercommunication portals using wireless system 100.

[0046] Base stations 104A-104C may form part of terrestrial basedcommunication systems and networks that include a plurality ofPCS/cellular communication cell-sites. They can be associated with CDMAor TDMA (or hybrid CDMA/TDMA) digital communication systems,transferring CDMA or TDMA type signals to or from remote stations.Signals can be formatted in accordance with IMT-2000/UMT standards,using WCDMA, CDMA2000 or TD-SCDMA type signals. On the other hand, basestations 104 can be associated with an analog based communication system(such as AMPS), and transfer analog based communication signals.

[0047] Remote stations 106A-106C each have or comprise apparatus or awireless communication device (WCD) such as, but not limited to, acellular telephone, a wireless handset, a data transceiver, or a pagingor position determination receiver. Furthermore, such remote stationscan be hand-held, portable as in vehicle mounted (including cars,trucks, boats, trains, and planes) or fixed, as desired. For example,FIG. 1 illustrates remote station 106A as a portable vehicle mountedtelephone or WCD, remote station 106B as a hand-held apparatus, andremote station 106C as a fixed device.

[0048] In addition, the teachings of the invention are applicable towireless devices such as one or more data modules or modems which may beused to transfer data and/or voice traffic, and may communicate withother devices using cables or other known wireless links or connections,for example, to transfer information, commands, or audio signals. Inaddition, commands might be used to cause modems or modules to work in apredetermined coordinated or associated manner to transfer informationover multiple communication channels. Wireless communication devicesremote stations are also sometimes referred to as user terminals, mobilestations, mobile units, subscriber units, mobile radios orradiotelephones, wireless units, or simply as ‘users,’ ‘phones,’‘terminals,’ or ‘mobiles’ in some communication systems, depending onpreference.

[0049] In the present example environment, remote stations 106A-106C andbase stations 104A-104C engage in wireless communications with otherelements in WCS 100 using CDMA communication techniques. Therefore,signals transmitted across the forward (to the remote stations) andreverse links (from the remote stations) convey signals that areencoded, spread, and channelized according to CDMA transmissionstandards. A forward CDMA link includes a pilot channel or signal, asynchronization (sync)-channel, several paging channels, and a largernumber of traffic channels. The reverse link includes an access channeland a number of traffic channels. The pilot signal is used to alertmobile stations of the presence of a CDMA-compliant base station. Thesignals use data frames having a predetermined duration, such as 20milliseconds. However, this is for convenience in description, and thepresent invention may be employed in systems that employ othercommunications techniques, such as time division multiple access (TDMA),and frequency division multiple access (FDMA), or other waveforms ortechniques as listed above, as long as the communication system ornetwork sends power control commands to the remote station.

[0050] In any case, the wireless signals need to be transmitted at powerlevels sufficient to overcome noise and interference so that thetransfer of information occurs within specified error rates. However,these signals need to be transmitted at power levels that are notexcessive so that they do not interfere with communications involvingother remote stations. Faced with this challenge, base stations andremote stations can employ dynamic forward link power control techniquesto establish appropriate forward link transmit power levels.

[0051] Conventional forward link power control techniques involve closedloop approaches where user terminals provide base stations with feedbackthat specifies particular forward link transmit power adjustments,referred to as up/down commands because they direct either a powerincrease or a power decrease. For example, one such approach involves auser terminal determining signal-to-noise ratios (SNRs) or bit errorrates (BER) of received forward link traffic signals, and requesting thebase station to either increase or decrease the transmit power oftraffic signals sent to the remote station based on the results. Inaddition to transmitting up/down commands, other types of informationmay be transmitted to base stations periodically including various powerand noise measurements to support operations, such as “handoffs” betweenbase stations.

[0052] Typically, base stations 104A-104C adjust the power of thesignals that they transmit over the forward links of WCS 100. This power(referred to herein as forward link transmit power) may be variedaccording to requests by, information from, or parameters for remotestations 106A-106C, and according to time. This time varying feature maybe employed on a frame-by-frame basis. Such power adjustments areperformed to maintain forward link BER or SNR within specificrequirements, reduce interference, and conserve transmission power.

[0053] Typically, remote stations 106A-106C also adjust the power of thesignals that they transmit over the reverse links of WCS 100, under thecontrol of control station 102 or base stations 104A-104C. This power(referred to herein as reverse link transmit power) may be variedaccording to requests by or commands from a BTS, received signalstrength or characteristics, or parameters for remote station operation,and according to time. This time varying feature may be employed on aframe-by-frame basis. Such power adjustments are performed to maintainreverse link bit error rates (BER) within specific requirements, reduceinterference, and conserve transmission power.

[0054] Examples of techniques for exercising power control in suchcommunication systems are found in U.S. Pat. No. 5,383,219, entitled“Fast Forward Link Power Control In A Code Division Multiple AccessSystem,” U.S. Pat. No. 5,396,516, entitled “Method And System For TheDynamic Modification Of Control Parameters In A Transmitter PowerControl System,” and U.S. Pat. No. 5,056,109, entitled “Method andApparatus For Controlling Transmission Power In A CDMA Cellular MobileTelephone System,” which are incorporated herein by reference.

[0055] III. Service Areas

[0056] As discussed, each base station has a service area 108(108A-108C) which can be generally described as the geographical extentof a locus of points for which a remote station 106 can communicateeffectively with the base station. As an example, when a remote station106 is within a service area 108, messages can be transmitted fromcontrol center 102 to a base station 104 (104A-104C) using a forwardlink 110 (110A-110C), and from base station 104 to a remote station 106using a forward link 112 (112A-112C). Messages are transmitted from aremote station 106 to a base station 104 over a return link 114(114A-114C). These messages are transmitted to the control center 102using a return link 116 (116A-116C).

[0057] Some or all of the communications between a base station 104 andcontrol station 102 can be carried over other wireless, such asmicrowave, radio, or satellite type links, or non-wireless transfermechanisms such as, but not limited to dedicated wireline services,optical or electronic cables and so forth, all indicated as line 118, ifdesired. Also, messages transmitted using forward links 110 and 112 aretypically modulated in different frequency bands or modulationtechniques than the messages transmitted over reverse links 114 and 116.The use of separate forward and reverse links allows full duplexcommunications between the control center 102 and the remote station106. TD-SCDMA systems use time division duplexing to accomplish theforward and reverse links, so a power controlled repeater could beimplemented using either time division duplexing or frequency divisionduplexing.

[0058] The service area of a base station is illustrated as generallycircular or elliptical in FIG. 1 for convenience. In actualapplications, local topography, obstructions (buildings, hills, and soforth), signal strength, and interference from other sources dictate theshape of the region serviced by a given base station. Typically multiplecoverage areas 108 (108A-108C) overlap, at least slightly, to providecontinuous coverage or communications over a large area or region. Thatis, in order to provide an effective mobile telephone or data service,many base stations would be used with overlapping service areas, wherethe edges have decreased power.

[0059] One aspect of the communication system coverage illustrated inFIG. 1, is the presence of an uncovered region 130, which can often bereferred to as a hole, or an uncovered region 132 which is simplyoutside of WCS 100 normal coverage areas. In the case of a “hole” incoverage, there are areas surrounding or at least adjacent to thecovered areas which can be serviced by base stations, here base stations104A-104C. However, as discussed above a variety of reasons exist forwhich coverage might not be available in regions 130 or 132.

[0060] For example, the most cost effective placement of base stations104A-104C might place them in locations that simply do not allow theirsignals to reliably reach or cover regions 130 or 132. Alternatively,topological features such as mountains or hills 134, man made structures136, such as tall buildings or urban canyons often created in centralurban corridors, or vegetation 138, such as tall trees, forests, or thelike, could each partially or completely block signals. Some of theseeffects can be temporary, or change over time, to make systeminstallation, planning, and use even more complex.

[0061] While it is possible to extend coverage of the cellular telephonenetwork 100 by simply adding more base stations 104 to cover additionalgeographical territory, it is sometimes very difficult and uneconomicalto do so. Not only are base stations relatively complex and costly orhard to cite, but regions sought to be covered may have irregular shapeswith unusual multi-path or fading characteristics that make using a basestation difficult. The area may also be a lower communication trafficdensity area where lower or only occasional use is anticipated.

[0062] In many cases, for example, the territory sought to be coveredhas enough traffic to justify the use of a repeater 120 but not a basestation. It may also be more amenable to using several repeaters tocover unusually shaped regions or circumvent the problems of blockage.In this situation, one or more repeaters 120 (120A, 120B) accepttransmissions from both a remote station 106 (106D) and a base station104 (104A), and act as an intermediary between the two, essentiallyoperating as a “bent pipe” communication path. Using a repeater 120, theeffective range of a base station 104 is extended to cover extendedservice area 132.

[0063] While the use of repeaters 120 is a more cost effective way toincrease range or coverage for base stations, it has some disadvantages.One major disadvantage that has been discovered, is the increase innoise for base stations servicing or using the repeater.

[0064] IV. Repeater Overview

[0065]FIG. 2 is simplified block diagram of a repeater 200. A moretypical commercial repeater would most likely have additional componentsincluding additional filtering and control elements to control noise,out of band emissions, and to regulate the gain. Repeater 200 includes adonor antenna 202 for receiving signals, a duplexor 204, an amplifier206 for amplifying signals received at the donor antenna, a secondduplexor 208, and a server or coverage antenna 212 for transmitting (orrepeating) signals received by the repeater 200. A second amplifier 216is also included which amplifies signals received at server antenna 206,and provides the amplified signals to the donor antenna.

[0066] The two duplexers (204, 208) are used to split or separate theforward link and reverse link signals (frequencies) to provide necessaryisolation between the two so that they do not enter the other processingchains of repeater 200. That is, to prevent transmissions from enteringreceivers, and so forth, and degrading performance. The receive orreceiver duplexer (204) is coupled to an antenna referred to as thedonor antenna (202), since it receives signals “donated” from anothersource, such as a base station, also referred to as a donor cell. Thedonor is more typically not a cell or cell site but a sector within acell being handled by the donor base station. The antenna coupled to theduplexer on the transmission or output side (208) of the repeaterprocessing is referred to as the output or coverage antenna (212).

[0067] For embodiments used in cellular phone or wireless communicationsystems, such as those mentioned above, a duplexer is chosen to operatein what is referred to as the 800 MHz band. Typically this would meanwith a forward link frequency of around 882.75 MHz and a reverse linkfrequency of around 837.75 MHz. However, these frequencies are dependentupon the specific system in which the repeater is used, as indicatedabove, and the duplexer would be chosen according, as would be known.For example PCS systems operate around 1900 MHz while typical GSMsystems around 1800 MHz and UMTS around 2100 MHz.

[0068] The isolation provided between the two frequencies is typicallygreater than 100 dB, which is sufficient to maintain repeater stability.The bandwidth of each link is typically on the order of 5 MHz. A smallerbandwidth is desirable to reject potential interference by signals fromFM, GSM, and other CDMA carriers. However, to achieve a smallerbandwidth, SAW filters are typically required, which is not asdesirable, so this may be avoided for many embodiments, as desired.

[0069] While the basic repeater can apparently act as a bent-pipe andtransfer signals back and forth, a problem has been discovered, asdiscussed above, related to repeater thermal noise contribution, hereincalled “push” at the BTS, and how fluctuations in repeater gain aregoing to adversely affect the push. It can be easily shown that it isundesirable to have a varying amount of thermal noise at the BTS, andembodiments of the invention allow a new type of reverse linkpower-control in the repeater that can maintain a substantially constantrepeater thermal noise push at the BTS.

[0070] V. Repeater Reverse Link Analysis

[0071] The effective noise factor of the repeater as well as that of theBTS under zero-load condition, can be used to derive a repeater thermalnoise push relationship. With the repeater thermal noise pushquantified, one can establish the relationship for maintaining aconstant repeater thermal noise push at the BTS. To accomplish thisanalysis, one can start with a WCS model 300, as shown in FIG. 3, whichshows two remote or mobile stations 306A and 306B communicating througha base station 304 and a repeater 320, respectively, in a modeledcommunication system 300. That is, a functional and parameter basedreplica of the operations performed within the WCS. Some parameters usedin this model are shown in Table I. TABLE I Parameter Definition GeneralT_(oI) Reference temperature which is equal to 290° K. K Boltzman'sConstant or 1.38 × 10⁻²³ Joules/Kelvin W Bandwidth of the signal. Inthis example, W = 1.228 MHz Repeater T_(aR) Antenna temperature of therepeater coverage antenna S_(c) Signal power at repeater coverageantenna connector N_(c) Noise power density at repeater coverage/serverantenna connectors G_(R) Gain of the repeater N_(R) Repeater additivenoise power density, N_(R) = k T_(eR) G_(R) F_(R) Repeater noise factor,F_(R) = 1 + T_(eR)/T_(o) T_(eR) Repeater effective noise temperature,T_(eR) = (F_(R) − 1) T_(o) G_(d) Gain of the repeater donor antenna PathLoss between BTS and Repeater L_(p) Path loss between repeater donorantenna and BTS antenna Base Station G_(a) BTS antenna gain T_(aB) BTSantenna temperature S_(O) BTS antenna connector signal power N_(O) BTSantenna connector noise power density G_(B) BTS gain S_(O) BTS outputsignal power N_(O) Noise power density at BTS output N_(B) Additivenoise power density of BTS, N_(B) = k T_(eB) G_(B) F_(B) Noise factor ofthe base station, F_(B) = 1 + T_(eB)/T_(o) T_(eB) Effective noisetemperature of BTS, T_(eB) = (F_(B) − 1) T_(o) G_(T) BTS-repeater linkgain, G_(T) = G_(R) G_(d) L_(p) G_(a) (assuming negligible cable losses,which could be added)

[0072] 1. Effective Noise Factor of Repeater

[0073] It is first very useful to determine the effective noise factorof the repeater, EF_(R), under zero-load condition. In looking at thesystem model shown in FIG. 3, the thermal noise density emanating fromthe repeater donor antenna is given by:

N _(repeater) =k(T _(aR) +T _(eR))G _(R) G _(d),   (1)

[0074] and the thermal noise contribution from the repeater at theoutput of the BTS is: $\begin{matrix}{N_{repeater}^{@{BTS}} = {N_{repeater}L_{p}G_{a}{G_{B}.}}} & (2)\end{matrix}$

[0075] In the absence of a repeater in the base station coverage area,the nominal thermal noise density at the output of the BTS is given by:

N _(O) ^(nom) =k(T _(aB) +T _(eB))G _(B).   (2)

[0076] With the addition of a repeater in the BTS coverage area, thetotal thermal noise density at the output of the BTS can be modeled asthe sum of a contribution from the repeater (Eq. 2) and the nominal case(Eq. 3). Therefore, we have: $\begin{matrix}{N_{O} = {N_{repeater}^{@{BTS}} + N_{O}^{nom}}} & (4)\end{matrix}$

[0077] which becomes: $\begin{matrix}\begin{matrix}{N_{O} = {{N_{repeater}L_{p}G_{a}G_{B}} + {{k\left( {T_{aB} + T_{eB}} \right)}G_{B}}}} \\{{= {{{k\left( {T_{aR} + T_{eR}} \right)}G_{R}G_{d}L_{p}G_{a}G_{B}} + {{k\left( {T_{aB} + T_{eB}} \right)}G_{B}}}},} \\{= {{{k\left( {T_{aR} + T_{eR}} \right)}G_{T}G_{B}} + {{k\left( {T_{aB} + T_{eB}} \right)}{G_{B}.}}}}\end{matrix} & (5)\end{matrix}$

[0078] From this relationship, one can see that the total thermal noisedensity at the output of the BTS reverts to a nominal case when: thepath loss, L_(P) between the repeater and the BTS increases and G_(T)approaches 0, the repeater signal is completely blocked from the BTS, orthe repeater is turned off.

[0079] From this model of the total thermal noise density at the BTSoutput, the effective noise factor of the repeater, EF_(R), is definedas the signal-to-noise ratio at repeater coverage antenna connector overthat at the output of the base station, which is: $\begin{matrix}{{{EF}_{R} = {\frac{{S_{c}/N_{c}}W}{{S_{O}/N_{O}}W} = {\frac{S_{c}}{S_{O}}\frac{N_{O}}{N_{c}}}}},{then}} & (6) \\{{EF}_{R} = {\frac{{{k\left( {T_{aR} + T_{eR}} \right)}G_{T}G_{B}} + {{k\left( {T_{aB} + T_{eB}} \right)}G_{B}}}{{kT}_{aR}G_{T}G_{B}}.}} & (7)\end{matrix}$

[0080] If T_(aR) is set equal to T_(o), the expression for the effectivenoise factor of the repeater becomes: $\begin{matrix}{{{EF}_{R} = \frac{{{k\left( {T_{o} + T_{eR}} \right)}G_{T}G_{B}} + {{k\left( {T_{o} + T_{eB}} \right)}G_{B}}}{{kT}_{o}G_{T}G_{B}}},{and}} & (8) \\{{EF}_{R} = {F_{R} + \frac{F_{B}}{G_{T}}}} & (9)\end{matrix}$

[0081] Due to presence of the BTS antenna, Equation 8 differs from thatfor a set of conventional noisy gain blocks since the noise contributionfrom both the BTS antenna and the repeater are present at the input ofthe BTS. In the absence of the BTS antenna, the effective noise factorof the repeater is: $\begin{matrix}{{EF}_{R} = {F_{R} + {\frac{F_{B} - 1}{G_{T}}.}}} & (10)\end{matrix}$

[0082] If we multiply the numerator and denominator of Equation 8 by thenominal thermal noise density of the BTS, we can re-arrange it toobtain: $\begin{matrix}{{EF}_{R} = {\frac{{{k\left( {T_{o} + T_{eR}} \right)}G_{T}G_{B}} + {{k\left( {T_{o} + T_{eB}} \right)}G_{B}}}{{k\left( {T_{o} + T_{eB}} \right)}G_{B}}\frac{{k\left( {T_{o} + T_{eB}} \right)}G_{B}}{{kT}_{o}G_{B}}{\frac{1}{G_{T}}.}}} & (11)\end{matrix}$

[0083] The first term of Equation 11 is the push exerted by a repeateron the nominal thermal noise density at the BTS, while the second termis simply the nominal noise factor of the BTS. Thus, if we defineP_(thermal) as the repeater thermal noise push at the BTS, we have:$\begin{matrix}{{P_{thermal} = \frac{{{k\left( {T_{o} + T_{eR}} \right)}G_{T}G_{B}} + {{k\left( {T_{o} + T_{eB}} \right)}G_{B}}}{{k\left( {T_{o} + T_{eB}} \right)}G_{B}}},{and}} & (12) \\{{EF}_{R} = {P_{thermal}{\frac{F_{B}}{G_{T}}.}}} & (13)\end{matrix}$

[0084] 2. Effective Noise Factor of BTS

[0085] In calculating an effective noise factor of the BTS, EF_(B),under zero-load condition, the thermal noise contribution from therepeater is modeled as another additive noise source at the output ofthe BTS. Therefore, the expression for the effective noise factor of theBTS is: $\begin{matrix}{{EF}_{B} = \frac{{{k\left( {T_{aR} + T_{eR}} \right)}G_{T}G_{B}} + {{k\left( {T_{aB} + T_{eB}} \right)}G_{B}}}{{kT}_{aB}G_{B}}} & (14)\end{matrix}$

[0086] Substituting T_(aR)=T_(aB)=T_(o)=290° K., this becomes:

EF _(B) =F _(R) G _(T) +F _(B).   (15)

[0087] and, it is evident that the effective repeater noise factor andthe effective BTS noise factor are related by the BTS-repeater linkgain,

EF_(B)=EF_(R)G_(T)   (16)

[0088] and, hence, in dB, the difference between effective BTS noisefigure and effective repeater noise figure equals G_(T), theBTS-repeater link gain. A review of the above relationships also showsthat as G_(T) increases, the effective repeater noise factor is going toapproach the nominal repeater noise factor. On the other hand, whenG_(T) decreases, the effective BTS noise factor is going to approach thenominal BTS noise factor.

[0089] 3. Repeater Thermal Noise Push

[0090] An expression can now be produced for the repeater thermal noisepush at the BTS in terms of nominal BTS noise factor, F_(B), nominalrepeater noise factor, F_(R), and BTS-repeater link gain, G_(T). Morespecifically, from Equations 9 and 13, one can see that: $\begin{matrix}{{{EF}_{R} = {{P_{thermal}\frac{F_{B}}{G_{T}}} = {F_{R} + \frac{F_{B}}{G_{T}}}}},{and}} & (17) \\{P_{thermal} = {{\frac{F_{R}}{F_{B}}G_{T}} + 1.}} & \quad\end{matrix}$

[0091] Equation 17 represents the repeater thermal noise push equation,which shows that repeater thermal noise push at the BTS is linear withrespect to BTS-repeater link gain. Moreover, the slope of P_(thermal)versus G_(T) is the ratio of nominal repeater noise factor over nominalBTS noise factor. However, looking at Equations 4 and 12 provide anotherperspective of the repeater thermal noise push since: $\begin{matrix}{P_{thermal} = {\frac{{{k\left( {T_{o} + T_{eR}} \right)}G_{T}G_{B}} + {{k\left( {T_{o} + T_{eB}} \right)}G_{B}}}{{k\left( {T_{o} + T_{eB}} \right)}G_{B}} = {\frac{N_{repeater}^{@{BTS}} + N_{O}^{nom}}{N_{O}^{nom}} = {\frac{N_{repeater}^{@{BTS}}}{N_{O}^{nom}} + 1}}}} & (18)\end{matrix}$

[0092] which can be used to assist in producing an effective process oralgorithm for operating a power-controlled repeater, as discussed below.

[0093] VI. Overview of Power Control in a Repeater

[0094] The above describes the rise that occurs in thermal noise levelat the BTS caused by the addition of a repeater in a BTS coverage area.This phenomena, as stated above, will result in fluctuations in thetotal amount of thermal noise at the BTS, and adversely affect coverageas well as service in both the BTS and repeater coverage areas. For aBTS with a repeater in its coverage area, it has been shown that theeffective repeater noise factor as well as the effective BTS noisefigure are related by the BTS-repeater link gain. From the effectiverepeater noise factor one can also see that the repeater thermal noisepush is linear with respect to the BTS-repeater link gain, and the slopeis given by nominal repeater noise factor over nominal BTS noise factor.

[0095] This phenomena, as stated above, will result in fluctuations inthe total amount of thermal noise at the BTS, and adversely affectcoverage as well as service in both the BTS and repeater coverage areas.Therefore, it is desirable to have the ability to detect and quantifychanges, and restore the gain of the repeater back to a pre-determinedlevel. That is, it is desirable to keep the gain of a repeaterrelatively constant.

[0096] It has been discovered that this can be accomplishedeconomically, with low complexity, by embedding a wireless communicationdevice, or equivalent circuitry or capability inside, that is within theoperating structure of, the repeater, and by injecting the reverse linksignal output of the embedded WCD into the reverse link of the repeater.With a common reverse link, WCD reverse link power-control can beutilized to calibrate the gain of the repeater. This provides for anautomatic setting of a repeater reverse link operating point through theuse of the reverse link power control of the built-in WCD, whichproduces a power-controlled repeater which, in conjunction with reverselink power-control, can maintain a substantially constant or lowfluctuation repeater thermal noise push at the BTS, and improve repeaterperformance.

[0097] With the embedded WCD, one can also establish periodic calls orcommunication sessions between the repeater and a base station, andutilize reverse link power-control for the WCD to calibrate orre-calibrate the gain of the repeater. This improves repeaterperformance in general and also allows the repeater to dial-inautomatically during repeater installation to establish and thenmaintain a desired operating point throughout a use period, which couldbe useful life, of the repeater. This effectively compensates forvariations in repeater-to-BTS path loss, environmental conditions,amplifier aging, and changes in user load that deleteriously impact thereverse link for the repeater.

[0098] The power-controlled repeater also stabilizes the reverse linkoperating point, essentially keeping remote stations in the repeatercoverage area from “hitting” the BTS with too much or too little power.

[0099] VII. Power-Controlled Repeater

[0100] A block-diagram of one embodiment of an exemplarypower-controlled repeater is shown in FIG. 4, and is described in termsof the basic elements used in implementing repeater forward and reverselinks. In FIG. 4, a repeater 400 is shown having a donor antenna 402 anda coverage antenna 414. Repeater 400 has a forward link that has twoduplexers 404 and 412, two amplifiers 406 and 410, a coupler 408, and afixed attenuator 416. However, fixed attenuator 416 is not required forimplementing all embodiments.

[0101] Repeater 400 is also shown having a reverse link that uses thetwo duplexers 404 and 412, a combiner 418, an amplifier 420, anadjustable or variable amplifier 422, and a fixed attenuator 424. Thevariable amplifier 422 could also be implemented using a variableattenuator. A wireless device or circuit 430 is shown coupled betweenthe two links (forward and reverse) having at least one output connectedto a processor or controller 432, shown as part of the reverse link.

[0102] The two duplexers 404 and 412 are used to split or separate theforward and reverse link signals, as discussed above, while combiner 418is used to add the output of the wireless device 430 embedded in therepeater, the transmit signal, to the repeater reverse link path. Thisallows the wireless device to communicate with at least one, andtypically only one, base station. An exemplary duplexor useful forcellular communication frequencies is manufactured by Celwave under thepart number 5043-8-3.

[0103] The combiner is placed at the input of the amplifier chain of thereverse link primarily to maintain repeater stability, although this isnot strictly necessary for every embodiment. Since the reverse linksignal levels are smallest at this location, the amount of reverse linkpower that is coupled to the repeater forward link through the repeaterwireless device loop is minimized. An exemplary combiner useful forimplementing embodiments is manufactured by Minicircuits under the partnumber ZFSC-2-2.

[0104] Coupler or power coupler 408 is used to couple some of theforward link power to an input for wireless device 430 embedded withinthe structure of repeater 400, which is discussed further below. Atypical value selected for signal power to be coupled into the wirelessdevice is 20 dB, a value that is generally considered sufficiently lowso as to not degrade forward link performance. However, depending on thedesign of the remainder of the repeater components, one skilled in theart can readily use a different coupling coefficient, as desired. Anexemplary coupler useful for implementing embodiments is manufactured byNarda under the part number 4242-20.

[0105] For the repeater forward link signal presented to the mobilephone 430, antenna 402, duplexer 404, amplifier 406 along with fixedattenuator 416, are used.

[0106] Fixed attenuator 416 is used to set the forward link gain in thisembodiment. The forward link gain is set for different repeater-to-BTSpath losses and different BTS transmit power levels. The adjustment canbe accomplished simply by manually inserting different coaxialattenuators, or use other more automated approaches that are known inthe art. The mobile 430 should be capable of implementing the powercontrol algorithm for the selected radio technology. For a typical CDMAmobile, the forward link power determines the open loop estimate forreverse link transmission level, so the design should satisfy thiscriteria with the power level of the forward link signal applied to themobile, and the value of attenuator 426.

[0107] The gain of the reverse link gain chain, comprising amplifier420, fixed attenuator 426, and adjustable amplifier 422, is used to setthe reverse link gain of the repeater. As part of this process, severalparameters are important. The repeater noise figure which is set suchthat it minimizes the push the repeater thermal noise has on the basestation thermal noise floor. This is accomplished primary by placingfixed attenuator 426 and adjustable amplifier 422 at the output. Thegain of the amplifiers is set high enough to minimize the influence theattenuators have on the repeater noise figure.

[0108] Fixed attenuator 426 is used to set the power level at which aremote station within repeater coverage “hits” or transfers signals tothe base station. The setting of this attenuator is described furtherbelow. Adjustable gain 422 is used to adjust the reverse link gain ofthe repeater to a desired, referred to as “correct,” operating pointduring repeater operation in the field. This setting is controlled bywhat is referred to as a repeater WCD or phone loop, which is describedfurther below.

[0109] A repeater phone loop consists of a repeater phone or WCD, amicro-controller, and the adjustable gain element on the reverse link(422), and possibly a fixed attenuator (426). When using repeater 400 ina CDMA type communication system, the repeater phone selected for thisembodiment would be an IS-95 CDMA, CDMA2000 1X, CDMA2000 1X/EV, or WCDMAtype wireless device, depending on the communication protocol beingused. A typical WCD 430 is discussed further below. However, otherdevice types would be used with other signal protocols, such as thosementioned above, as would be well understood.

[0110] WCD or phone 430 is used to communicate with a BTS, receivecalls, interpret BTS power control commands, and transmit data.Essentially, it behaves like any other CDMA phone in a communicationssystem or network. One significant difference in the repeater phone, ascompared to a typical CDMA remote station, is that the repeater reverselink amplifier chain is used as the repeater phone transmit amplifier.Power control functions for the repeater phone are performed by thisamplifier chain and not by an internal WCD or phone transmit amplifier.This gives the repeater phone the ability to power control the reverselink gain of the repeater.

[0111] This is accomplished in one embodiment by intercepting, orbreaking out the internal automatic gain control (AGC) signal generatedwithin the repeater WCD or phone. Essentially, the AGC line in the WCDis broken at a transmit amplifier input and routed to the adjustablegain amplifier 422 (G4) after passing through a micro-controller. Thisis easily accomplished through re-design of the WCD for this function,or even through retrofitting a device by simple modification of circuitconnects to couple the AGC signal line to a connector for furtherconnection to circuitry in the repeater. Those skilled in the art willreadily understand how to achieve such modifications. The internalrepeater WCD transmit amplifier is then used as a “fixed gain”pre-amplifier to the repeater reverse link amplifier chain, since theAGC signal will no longer be adjusting its output power. In one CDMAembodiment, the gain of the repeater WCD transmit amplifier is set totransmit at around −50 dBm at the WCD transmit output port, which wouldnormally be an antenna output. This transmit power level is typically aminimum transmit power level for the repeater WCD, and is selected forrepeater stability.

[0112] It is desirable to have the amplifier output for at leastamplifier 422 selected to be relatively high when the repeater is placedat or very near the edge of cell coverage for a BTS. One embodiment setsthe amplifier about 10 dB below an expected peak value as the generalmaximum value which allows the repeater to be installed at the edge ofBTS coverage and still have 10 dB of swing to compensate for such thingsas temperature drift and repeater amplifier aging. This 10 dB minimumattenuation of the amplifier gain is a conservative estimate that shouldbe sufficient to ensure good repeater functionality.

[0113] Micro-controller 432 is used to achieve several WCD operations ormanipulations that might otherwise be provided by a WCD user, or anautomated system. For example, micro-controller 432 communicates withWCD or phone 430 to answer or attempt to open a communication link whenthere is an incoming “call,” to send power control commands from WCD 430to amplifier 422 throughout the call, to latch the amplifier outputlevel once power control settles, and to then “hang-up the phone” orotherwise terminate service or tear down a call when a link is no longerdesired or appropriate.

[0114] Micro-controller 432 may be implemented primarily in hardwareusing, for example, a software-controlled processor or controllerprogrammed to perform the functions described herein, a variety ofprogrammable electronic devices, or computers, a microprocessor, one ormore digital signal processors (DSP), dedicated function circuitmodules, and hardware components such as application specific integratedcircuits (ASICs) or programmable gate arrays (PGAs). Implementation of ahardware state machine so as to perform the functions described hereinwill be apparent to persons skilled in the relevant art(s).Micro-controller 432, as discussed below, may be implemented within theWCD to save hardware, if the WCD has sufficient processing power.Micro-controller 432 is shown in 400 to illustrate the function, andcould be external to the WCD 430, or internal to the WCD.

[0115] Where embodiments are implemented using software, the softwarecan be stored in a computer program product and loaded into the systemusing a removable storage drive, memory chips or communicationsinterface. The control logic (software), when executed, causes thecontroller to perform certain functions as described herein.

[0116] The micro-controller receives the reverse link gain controlcommands from WCD 430, slows the commands down below about a 800 dB/sec.rate, and outputs the commands to amplifier 422. The slowing down of thepower control commands is done in order to keep the power control ofremote stations in the repeater coverage area from fighting against thepower control of WCD 430.

[0117] Since remote stations in the repeater coverage area are passingthrough the repeater reverse link, any change in the repeater reverselink will cause the BTS to send power control commands to these remotestations to compensate. If WCD 430 is in the process of changing therepeater reverse link gain with power control, and the transmit power ofremote stations in repeater coverage has not settled, then these remotestations can create additional interference at the BTS. Thisinterference causes additional power control commands to go out to allremote stations, including WCD 430, having an unstable effect.

[0118] This potential instability is stabilized by having WCD 430control the reverse link gain of repeater 400 at a much slower rate thanthe power control of remote stations in repeater coverage. Essentially,sufficient time is allowed between repeater reverse link gainadjustments to allow remote stations to settle their own power controlvalues.

[0119] In one embodiment, a power control rate for the repeater reverselink gain is set at around 80 dB/sec., which is about ten times, slowerthan the power control rate experienced by typical CDMA type remotestations in repeater coverage. This is a conservative estimate thatshould be sufficient to maintain power control stability. For othertypes of communication signal standards such as those that are GSM orTDMA based, the power control rate appears to generally be even slower,so a power control rate for those systems would need to be designed withan appropriate value or rate.

[0120] Generally, a call will be placed from another phone, modem or WCD(as in BTS) to WCD 430 and this call should be maintained for a minimumamount of time. This time window should be sufficient to allowmicro-controller 432 to adjust the gain of amplifier 422 and settle thereverse link gain to its correct operating point before the call ends.This assumes the BTS will maintain this call for a minimum of around 30seconds, and that the repeater micro-controller will make amplificationadjustments within about a 20 second window. These are conservativeestimates that should be sufficient to reasonably guarantee goodfunctionality in a typical repeater design, and can be changedaccordingly.

[0121] In a commercial repeater, the micro-controller could also be usedfor repeater alarm monitoring, and other functions, as desired.

[0122] As mentioned above, fixed attenuator 426 is used to set how thepower level a remote station in repeater coverage hits the BTS. It isdesirable to have remote stations in repeater coverage initially hit theBTS at a power level below their required E_(b)/N_(t). This ensures thatthe remote stations in repeater coverage will not create additionalinterference by hitting the BTS with excessive power. In one embodiment,the value chosen for attenuator 426 is such that the transmitted powerlevel of a remote station in repeater coverage will hit the BTS about 5dB below its required E_(b)/N_(t). This value is selected as a closedloop adjustment factor. The remote station in repeater coverage willreach its required E_(b)/N_(t) after closed loop power control engagesand settles. It is assumed that the required E_(b)/N_(t) for a remotestation in repeater coverage is about 6 dB and that this E_(b)/N_(t)corresponds to a frame error rate of around 1%, as typically required bythe BTS, although other rates could easily be used, as desired. Thesevalues are chosen as a starting point and may change after empiricaldata is collected, since it is understood that the required E_(b)/N_(t)can change depending on conditions in the network or communicationsystem.

[0123] As is desired for the situation where a remote station is inrepeater coverage, it is likewise desirable to have WCD 430 initiallyhit the BTS at a power level below its required E_(b)/N_(t) to ensurethat the WCD will not create additional interference at the BTS.Therefore, the variable gain amplifier is set such that the transmittedpower level of the repeater phone hits the BTS 10 dB below its requiredE_(b)/N_(t), or to a closed loop adjustment factor of 10 dB. This 10 dBvalue is chosen to accommodate the 10 dB minimum required attenuation ormargin discussed earlier. If the minimum margin of the amplifier islowered, as may happen after or in response to the gathering ofempirical data and or system testing, then the closed loop correctionfactor can also be lowered by the same amount.

[0124] While a variable gain amplifier 422 is shown in FIG. 4, it shouldbe understood by those skilled in the art that other techniques are alsoavailable for effectively controlling output power. For example, a fixedgain amplifier can be used in place of amplifier 422 with a variableattenuator placed in series with the input, to adjust the amount ofsignal gain by adjusting the input signal power level, as mentionedabove. This is illustrated in FIG. 5, where a repeater 500 is shownusing many of the same elements as repeater 400 with changes made toaccommodate alternative signal processing and signal coupling for theWCD.

[0125] In FIG. 5, a step attenuator 522 is used with a fixed amplifier524 in place of variable gain amplifier 422. Control signals or commandsfrom micro-controller 432 act to change the value of step attenuator 522input to adjust the amount of signal gain by adjusting the input signalpower level. A step attenuator such as one available from Weinschelunder model number 3206-1, may be used for this function.

[0126] In addition, the repeater of FIG. 5 is configured to interactwith a WCD that operates more like an independent phone, which wouldinclude circuitry for driving or transferring signals through anantenna. Here, a more complete or actual phone can be used in therepeater by using a cradle or such device to secure the phone in placeand provide interconnections to external circuitry within the repeater.In this situation, although not necessary, it is more likely a separatemicro-controller 432 will be used. It is also possible that alternativemeans of coupling signals into and out of the phone may be used.

[0127] In this alternative configuration, signals may be coupled intoand out of the phone using a circulator 514 to transfer signals to andfrom a repeater phone 530 antenna or antenna connector, or similarinput/output. A circulator such as one available from Ute Microwaveunder model number CT-1058-0, may be used for this function. Circulator514. The circulator is used to split the repeater phone receive andtransmit signals, and to provide isolation between these two signals.The circulator selected for this design typically has an isolation ofabout 20 dB, which is sufficient to ensure repeater stability.

[0128] Two attenuators 516 and 526 are also shown in FIG. 5. Attenuator516 can be used to adjust the amount of power being transferred intocirculator 514, while attenuator 526 is used to adjust the amount ofpower being transferred into combiner 418, in a similar manner topreviously described attenuators, 416 and 426, respectively.

[0129] VIII. Typical Wireless Communications Device

[0130] Two typical wireless communication devices useful forimplementing WCD 430 are shown in FIGS. 6 and 7.

[0131] In FIG. 6, a repeater phone 630 is shown having a modem 602 whichreceives input signals from an analog or digital, signal receiver 604which is in turn connected to receive input signals from fixedattenuator 416, discussed above. An exemplary modem would be one ofseveral well known mobile stations modems (MSM) manufactured by QualcommIncorporated, under model numbers such as MSM 3100, MSM 5xxx (5050,5100, 5200, 5500, etc.) or 6xxx (6050, 6100, 6200, 6500, etc.) for usein CDMA phones. Repeater phone 630 also has an AGC output which isdirected to a transmission power amplifier 608, typically through an RCfilter 606. The AGC signal is transferred along an AGC control line 610.Control line 610 is shown in FIG. 6 as having a break 612, which issymbolic of the change that is implemented in making a phone useful forembedding in repeater 400. The AGC line is redirected to form an AGCoutput 616 which is transferred to micro-controller 432, as discussedabove. Generally, in order to set the transmission circuitry oramplifier to a desirable minimum level of output, the input used for theAGC signal can be connected to a ground level point 614.

[0132] It should be noted that micro-controller 432 can be separate fromrepeater phone 630, or contained as part of repeater phone 630 if theprocessing power of the repeater phone has sufficient capability. Forexample a typical CDMA wireless device uses one or more integratedcircuits that employ embedded processors that are quite powerful, and acertain amount of associated memory or program storage. For example,some embodiments may include an embedded ARM-type processor or the like.Such elements can be used to implement the functions associated withmicro-controller 432 and provide a connection or signals output tocontrol the operation of variable gain amplifiers or signal attenuators.For this reason a dashed line 632 is used to indicate that the functionsor operation of micro-controller 432 are incorporated within thecommunication device being used.

[0133]FIG. 6 also shows the output/input lines 618 that connect tocircuitry associated with or in modem 602 that provide a callnotification, such as indicating the phone is “ringing”, although aringer is not generally useful in this application, and for providingsignals to the modem to either “pick-up” or “hang-up” the connection forthe phone. This input is provided from the microprocessor since there isno longer a series of buttons being pushed by a phone user to make thesechoices.

[0134] In addition, while modem 602 may contain a controller andinternal memory for accommodating commands and operations describedherein, one or more separate or additional memory or storage element 620may also be included within repeater phone 630 to provide locations forstoring commands, data, instructions, and so forth, as desired. Memoryrefers to any processor-readable medium including, but not limited to,RAM, ROM, EPROM, PROM, EEPROM, disk, floppy disk, CD-ROM, DVD, or thelike, on which may be stored a series of instructions executable by aprocessor.

[0135]FIG. 7, a typical spread spectrum wireless user terminal 700 isshown which uses an analog receiver 704 to receive, down-convert,amplify, and digitize received signals. Digital communication signalsoutput by analog receiver 704 are transferred to at least one digitaldata receiver 706A and at least one searcher receiver 708. Additionaldigital data receivers 706B-706N can be used to obtain desired levels ofsignal diversity, depending on the acceptable level of unit complexity,as would be apparent to one skilled in the relevant art.

[0136] At least one control processor 720 is coupled to digital datareceivers 216A-216N along with the searcher receiver 718, to provide,among other functions, basic signal processing, timing, power andhandoff control or coordination. Another basic control function oftenperformed by control processor 720 is the selection or manipulation ofPN code sequences or orthogonal functions to be used for processing CDMAcommunication signal waveforms. Control processor 720 signal processingcan include determination of relative signal strength and computation ofvarious related signal parameters, which may include the use ofadditional or separate circuitry such as received signal strengthindicator (RSSI) 714.

[0137] Outputs for digital data receivers 706A-706N are coupled todigital baseband circuitry 712 within the subscriber unit. User digitalbaseband circuitry 712 normally uses processing and presentationelements to transfer information to and from a terminal user, such assignal or data storage elements such as transient or long term digitalmemory; input and output devices such as display screens, speakers,keypad terminals, and handsets. These elements are not necessary in thisapplication, except for field servicing perhaps. Also included is A/Delements, vocoders and other voice and analog signal processing elementsthat all from parts of the terminal baseband circuitry, using elementswell known in the art. If diversity signal processing is employed, userdigital baseband circuitry 712 can comprise a diversity combiner anddecoder. Some of these elements may also operate under the control of,or in communication with, control processor 710.

[0138] In addition, while baseband circuitry 712 normally containsmemory for accommodating commands and operations described herein, oneor more separate or additional memory or storage elements 722 (such asdiscussed above) may also be included within repeater phone 700 toprovide locations for storing commands, data, instructions, and soforth, as desired.

[0139] When voice or other data is prepared as an output message orcommunications signal originating with the subscriber unit, user digitalbaseband circuitry 712 is used to receive, store, process, and otherwiseprepare the desired data for transmission. In the present applicationsuch data would be minimal and used simply for establishing acommunication link or indicating detected signal strength. Basebandcircuitry 712 provides this data to a transmit modulator 716 operatingunder the control of control processor 710, which has an outputconnected to a digital transmit power controller 718 which providesoutput power control to an analog transmit power amplifier 730 for finaltransmission. Information on the measured signal strength for receivedcommunication signals or one or more shared resource signals can be sentto the base station using a variety of techniques known in the art, forexample, by appending the information to other messages prepared bybaseband circuitry 712. Alternatively, the information can be insertedas predetermined control bits under control of control processor 710.

[0140] Analog receiver 704 can provide an output indicating the power orenergy in received signals. Alternatively, received signal strengthindication element 714 can determine this value by sampling an output ofanalog receiver 704 and performing processing well known in the art. Innormal use this information can be used directly by transmit poweramplifier 720 or transmit power controller 718 to adjust the power oftransmitted signals. This information can also be used by controlprocessor 710 to create AGC control signals for these other elements.

[0141] Digital receivers 706A-N and searcher receiver 708 are configuredwith signal correlation elements to demodulate and track specificsignals. Searcher receiver 708 is used to search for pilot signals,while digital receivers 706 A-N are used to demodulate other signals(traffic) associated with detected pilot signals. Therefore, the outputsof these units can be monitored to determine the energy in the pilotsignal or other shared resource signals. Here, this is accomplished alsousing either signal strength indication element 714 or control processor710.

[0142] As has already been suggested by FIGS. 4 and 5, the elementsshown for the WCD's in FIGS. 6 and 7 can form part of a simple controlmodule or device as opposed to a more complete “phone”. In this case, asstated earlier, the device can be designed to accept signals withincertain power ranges or amplitudes and timing, and as such theattenuator 416 or 426 may not be used, either one or both.

[0143] For the present invention, it is the ability to receive signalsfrom a BTS, operate on or respond to those signals, and generate or useappropriate power commands or signals, which may include power up/downcommands, that is important to the operation of the embedded WCD.Therefore, aside from this power control functionality being implementedby WCD 430, extraneous elements for processing other signals, such asscreen displays, ring tones, music, video, etc. are not necessary tothis function. In addition, when using a less complex module approach todesigning WCD 430, the processor or controller used in WCD 430 is morelikely to have sufficient or even extra power or processing cyclesavailable to perform the functions of both WCD 430 and micro-controller432, which is useful in reducing costs and complexity. In addition,memory and other elements that may be used for storing informationassociated with other operations, can also be released to handling powercontrol functions.

[0144] IX. Analysis of Operation of Power Controlled Repeater

[0145] With a repeater in a BTS coverage area, under consistent loadingcondition, and in the absence of jammers, the reverse link E_(b)/N_(o),equation, under perfect power-control, for a remote station is:$\begin{matrix}{{\frac{E_{b}}{N_{o}} = {\frac{S}{{\frac{\left( {M - 1} \right){\upsilon \left( {1 + i} \right)}}{W}S} + \left( {N_{repeater}^{@{BTS}} + N_{O}^{nom}} \right)}\frac{1}{R}}},} & (19)\end{matrix}$

[0146] where S is the received signal power of the remote station, M isthe number of users, ν is a voice activity factor, and i is the ratio ofinterference from other sectors.

[0147] If S_(R) is defined to be the transmit power of the embedded WCD,then the E_(b)/N_(o) for the embedded WCD in the power-controlledrepeater is: $\begin{matrix}{\frac{E_{b}}{N_{o}} = {\frac{S_{R}G_{T}G_{B}}{{\frac{\left( {M - 1} \right){\upsilon \left( {1 + i} \right)}}{W}S_{R}G_{T}G_{B}} + \left( {N_{repeater}^{@{BTS}} + N_{O}^{nom}} \right)}{\frac{1}{R}.}}} & (20)\end{matrix}$

[0148] which in terms of the repeater thermal noise push, P_(thermal),is: $\begin{matrix}{\frac{E_{b}}{N_{o}} = {\frac{S_{R}G_{T}G_{B}}{{\frac{\left( {M - 1} \right){\upsilon \left( {1 + i} \right)}}{W}S_{R}G_{T}G_{B}} + {N_{O}^{nom}P_{thermal}}}{\frac{1}{R}.}}} & (21)\end{matrix}$

[0149] With a perturbation of γ in the repeater reverse link gain (G3and G4 in FIG. 4), both the BTS-repeater link gain and the repeaterthermal noise contribution at the BTS are going to be perturbed by γ aswell. If reverse link closed-loop power-control requests a change of αin the transmit power of the embedded WCD to achieve the sameE_(b)/N_(o) as that in Equation 20, then: $\begin{matrix}{\frac{E_{b}}{N_{o}} = {\frac{\left( {\alpha \quad S_{R}} \right)\left( {\gamma \quad G_{T}} \right)G_{B}}{{\frac{\left( {M - 1} \right){\upsilon \left( {1 + i} \right)}}{W}\left( {\alpha \quad S_{R}} \right)\left( {\gamma \quad G_{T}} \right)G_{B}} + \left( {{\gamma \quad N_{repeater}^{@{BTS}}} + N_{O}^{nom}} \right)}{\frac{1}{R}.}}} & (22)\end{matrix}$

[0150] From the above equations one can describe the change in repeaterthermal noise push at the BTS that corresponds to the perturbation inthe repeater reverse link gain. More specifically, let ρ be the changein repeater thermal noise push at the BTS. Therefore: $\begin{matrix}{{{N_{O}^{nom}\left( {P_{thermal}\rho} \right)} = {{\gamma \quad N_{repeater}^{@{BTS}}} + N_{O}^{nom}}},} & (23) \\{{{P_{thermal}\rho} = {\frac{{\gamma \quad N_{repeater}^{@{BTS}}} + N_{O}^{nom}}{N_{O}^{nom}} = {{{\frac{N_{repeater}^{@{BTS}}}{N_{O}^{nom}}\gamma} + 1} = {{\left( {P_{thermal} - 1} \right)\gamma} + 1}}}},} & (24)\end{matrix}$

$\begin{matrix}{\rho = {\frac{{\left( {P_{thermal} - 1} \right)\gamma} + 1}{P_{thermal}}.}} & (25)\end{matrix}$

[0151] with substitution from above, one can obtain: $\begin{matrix}{\frac{E_{b}}{N_{o}} = {\frac{S_{R}G_{T}{G_{B}({\alpha\gamma})}}{{\frac{\left( {M - 1} \right){\upsilon \left( {1 + i} \right)}}{W}S_{R}G_{T}{G_{B}({\alpha\gamma})}} + {N_{O}^{nom}{P_{thermal}(\rho)}}}{\frac{1}{R}.}}} & (26)\end{matrix}$

[0152] From Equation 26, in order to achieve the same E_(b)/N_(o) asthat in previous expressions under perfect power-control, it is evidentthat αγ=ρ. Therefore: $\begin{matrix}{{{\alpha \quad \gamma} = {\rho = \frac{{\left( {P_{thermal} - 1} \right)\gamma} + 1}{P_{thermal}}}},{{{and}\quad \gamma} = {\frac{1}{{P_{thermal}\left( {\alpha - 1} \right)} + 1}.}}} & (27)\end{matrix}$

[0153] From Equation 27, given the nominal repeater thermal noise pushat the BTS, we could estimate and offset the change in repeater reverselink gain from the change in the transmit power of the embedded WCD,and, therefore, maintain a substantially constant repeater thermal noisepush at the BTS. The relationship between γ and α for repeater thermalnoise push at the BTS, with push values of 1, 2, and 3 dB is shown inFIG. 10, as lines 1002, 1004, and 1006, respectively.

[0154] X. Design of Power-Controlled Repeater

[0155] There are several specific issues to be considered when onedesigns a power-controlled repeater for a given system, using knownfeatures and parameters of the communication system with which it is tobe used. These relate to forward link power amplifier output in therepeater, repeater gain, distribution of gain on the forward link,distribution of gain on the reverse link, nominal noise factor of therepeater, and distribution of gain for the embedded wirelesscommunication device.

[0156] 1. Forward Link Power Amplifier Output

[0157] The design parameters for a forward link power amplifier outputare primarily driven by the size of the desired geographical coverage orservice area. This output is typically expressed in terms of the maximumaverage power, W_(R). However, since the instantaneous power on theforward link of the repeater can be substantially higher than W_(R),embodiments select or set the forward link power amplifier outputcapability to be as high as the maximum instantaneous power of therepeater. While not strictly required, this should be done to avoidsaturation, and the maximum instantaneous power is related to themaximum average power by the peak-to-average ratio in CDMA networks.

[0158] 2. Repeater Gain

[0159] In calculating the gain of a repeater, one can assume that theforward link gain G_(F) and the reverse link gain G_(R) aresubstantially identical. The BTS-repeater link gain, G_(T), is simplythe ratio of the target forward link power amplifier output, W_(R), andthe power amplifier output of the BTS, W_(B), which has a typical valueof 25W.

[0160] To derive the gain of the repeater, G_(R), one divides G_(T), bythe gain of the repeater donor antenna, G_(d), the target path lossbetween the repeater donor antenna and the base station antenna, L_(p),and the antenna gain of the base station antenna, G_(a). Therefore,G_(R) can be expressed as: $\begin{matrix}{G_{R} = {\frac{G_{T}}{G_{d}L_{p}G_{a}} = {\frac{W_{R}}{W_{B}}{\frac{1}{G_{d}L_{p}G_{a}}.}}}} & (28)\end{matrix}$

[0161] 3. Distribution of Gain on the Repeater Forward Link

[0162] From FIG. 4, in dB, the forward link gain of the power-controlledrepeater can be decomposed into:

G _(R) =G1+G2+Coupler Loss+2 (Duplexer Loss).   (29)

[0163] In selecting the value G1 for amplifier 406, a forward linkcoupler (408) to the embedded WCD, and the forward link attenuator (426)for the embedded WCD, it is important to ensure that the embedded WCDreceives an adequate amount of forward link overhead channel power (foruse by signals such as pilot, paging, and synchronization in a CDMAsystem), and the minimum requirement for accomplishing this is generallyon the order of −85 dBm for a CDMA type communication system, othertypes of systems or protocols can have different values..

[0164] 4. Distribution of Repeater Gain on the Reverse Link

[0165] Since it can be safely assumed the forward link and reverse linkgains are essentially identical (or enough so for the relationships tohold), the reverse link gain of the power-controlled repeater is G_(R)as well, and, from FIG. 4, we can see that in dB, it can be decomposedinto:

G _(R) =G3+G4+Combiner Loss+2(Duplexer Loss).   (30)

[0166] From above, WCD 430 is going to adjust the value G4 of amplifier422 to maintain a substantially constant repeater thermal noise push atthe BTS. Theoretically, changing G4 is going to alter the nominal noisefactor of the repeater, F_(R). However, one can safely assume that F_(R)is constant, and you can make F_(R) essentially constant by allocatingsufficient gain in amplifier 420 (G3).

[0167] Specifically, from the anticipated changes in G4 (Per WCD), andthe anticipated noise factor of amplifier 422 (G4), you can calculate byhow many dB the value of gain G3 should exceed the nominal G4 value inorder for F_(R) to vary less than some pre-determined amount. Forexample, if it is expected that G4 will change by 10 dB, and, from theanticipated noise factor of G4, it is concluded that G3 should exceedthe nominal G4 by around 40 dB in order for F_(R) to vary less than 1%,then there is a constraint of:

G3=G4+10 dB+40 dB=G4+50 dB.   (31)

[0168] which means the expression for G_(R), in dB, becomes:

G _(R)=(G4+50 dB)+G4+Combiner Loss+2(Duplexer Loss), and

G4=0.5(G _(R)−Combiner Loss−2(Duplexer Loss)−50 dB).   (32)

[0169] Therefore, once the value for gain G4 is determined, the gain G3can be obtained from Equation 31, noting that other values for changesin gain (G4), or how much one gain should exceed another (G3, G4) for agiven variation percentage (F_(R)) would be used, as desired or needed.

[0170] 5. Nominal Noise Factor of Repeater

[0171] A nominal noise factor of the repeater, F_(R), can be derivedfrom the constraint placed by the open-loop turn around constant, k. InCDMA communication systems, the open-loop turn around constant, k, is“hard-wired” in the wireless communication device for known reasons, andits first three terms are:

k=(pt)_(C)−134+(NF)_(C)+. . . ,

[0172] where:

[0173] (pt)_(C)=10 log₁₀(W_(B))=Maximum BTS power amplifier output(dBm), and

[0174] (NF)_(C)=10 log₁₀(F_(B))=BTS noise figure (dB).

[0175] For a remote station in the repeater coverage area, (pt)_(C)should be the forward link power amplifier output of the repeater, 10log₁₀(W_(R)). Furthermore, (NF)_(C) should convey the effective noisefigure of the repeater. However, since k is “hard-wired” in the remotestation, one can set (NF)_(C) to offset the change in (pt)_(C). Morespecifically, for the remote stations in the repeater coverage area, wehave (NF)_(C) ^(repeater) instead, and$({NF})_{c}^{repeater} = {{{10{\log_{10}\left( F_{B} \right)}} + \left\lbrack {{10{\log_{10}\left( W_{B} \right)}} - {10{\log_{10}\left( W_{R} \right)}}} \right\rbrack} = {10{\log_{10}\left( {F_{B}\frac{W_{B}}{W_{R}}} \right)}({dB})}}$

[0176] Therefore, to keep the “hard-wired” open-loop turn aroundconstant, k, valid from the perspective of the remote stations in therepeater coverage area, one should consider aiming for an effectiverepeater noise factor of: $\begin{matrix}{{EF}_{R} = {F_{B}{\frac{W_{B}}{W_{R}}.}}} & (33)\end{matrix}$

[0177] which becomes: ${EF}_{R} = {F_{R} + {\frac{F_{B}}{G_{T}}.}}$

[0178] since the BTS-repeater link gain (G_(T)) is set to the ratio ofrepeater forward link power amplifier output over BTS power amplifieroutput, this produces: $\begin{matrix}{{EF}_{R} = {{F_{R} + \frac{F_{B}}{\frac{W_{R}}{W_{B}}}} = {F_{R} + {F_{B}{\frac{W_{B}}{W_{R}}.}}}}} & (34)\end{matrix}$

[0179] While looking at these relationships it might appear one cannotexactly meet the condition stated in Equation 33, but they should beable establish an effective repeater noise factor that is close to thedesired value if:$F_{R}{\operatorname{<<}F_{B}}{\frac{W_{B}}{W_{R}}.}$

[0180] 6. Distribution of Gain for the Embedded WCD

[0181] For the embedded WCD, the gain of its forward link path in therepeater should be equal to the gain of its reverse link path in therepeater. Specifically, the reverse link attenuator (426) of embeddedWCD 430, ATT2, should be set such that:

G1+Coupler Loss+ATT1=ATT2+Combiner Loss+G3+G4.   (35)

[0182] XI. Deployment of Power-Controlled Repeater

[0183] The deployment of a power-controlled repeater is shown in FIG. 8,and is very similar to that of a conventional repeater, with only oneextra step being involved. That extra step is to place a call on theembedded WCD to establish a reference transmit power to go with thenominal repeater thermal noise contribution at the BTS. Otherwise, asshown in FIG. 8, to deploy a power-controlled repeater, it is firstphysically installed or cited within a desired service area in a step800, then the forward link gain of the repeater is adjusted in a step802 to achieve target forward link power amplifier output, the reverselink gain of repeater or BTS is adjusted in a step 804 to balance theforward link and the reverse link, and a reference transmit power of theembedded WCD is established in a step 806. While the installationprocess ends in step 808, periodically a “call” maybe placed in a step810 to a BTS to update the repeater settings based on changes in pathcharacteristics and such.

[0184] 1. Set Repeater Forward Link Power Amplifier Output

[0185] As mentioned earlier, the target repeater forward link poweramplifier output, W_(R), is driven by the size of the desired coveragearea. To meet W_(R), the value of G2 for amplifier 410 in FIG. 4 isadjusted, since the gain G1 of amplifier 406 is selected to provideadequate forward link overhead channel power to the embedded WCD 430.

[0186] 2. Balance Forward Link and Reverse Link

[0187] With the forward link gain of the power-controlled repeater set,the next step is to balance the forward link and the reverse link inboth the BTS and repeater coverage areas. The reverse link gain of theBTS is adjusted to accomplish this task since adjusting the reverse linkgain of the repeater is going to leave the forward link and the reverselink of the BTS coverage area unbalanced.

[0188] However, if it is not generally possible to adjust the reverselink gain of the BTS, then the value of gain G3 for amplifier 410 inFIG. 4 can be adjusted to balance the links since you should keep mostof the repeater's reverse link gain in the value of G4.

[0189] Once the forward link and the reverse link are balanced, thenominal repeater thermal noise push at the BTS is set as well.

[0190] 3. Establish Reference Transmit Power of Embedded Subscriber Unit

[0191] From the previous section, the nominal repeater thermal noisepush at the BTS is set after the forward link and the reverse link arebalanced. With the nominal push in place, the last step in deployment isto place a call on the embedded phone or WCD to establish a referencetransmit power to go with the nominal push.

[0192] After deployment, periodic calls can be made on the embedded WCDto detect, estimate, and offset changes in the reverse link gain of therepeater.

[0193] XII. Multi-Frequency Repeater

[0194] While the embodiments discussed above show that using a powercontrolled repeater achieves lower noise levels in a base stationcommunicating with or through the repeater, additional advantages may berealized by employing multiple frequency repeaters. That is, therepeater is capable of communicating on two, or more, frequencies ƒ₁ andƒ₂.

[0195] The above discussion used a single center frequency ƒ₁ forsignals transferred between the base station and the repeater, which isthe same as the frequency being used to transfer signals between therepeater and remote stations. That is, aside from potentially splittingthe forward and reverse links onto separate channels, the remotestations are configured to interact or communicate with the repeater atthe same frequencies that they would use in communicating with the basestation.

[0196] This is how a repeater is typically configured and makes sensewhere it is assumed remote stations may move into and out of cells orsectors, and may be communicating with base stations from time to timeand not repeaters. There is a desire to maintain operations with remotestations somewhat uniform so that base stations and repeaters do notrequire additional complexity to handle communications. In addition,there is a need to see that the communication devices can beaccommodated without undue change or complexity likewise being added tothem.

[0197] However, if the repeater communicates with either the remotestations or the base station at a second frequency ƒ₂, then thecommunication system may achieve improved loading or additional capacityas the remote stations handled by the repeater or the repeater itselfprovides lower interference to the BTS and remote stations.

[0198] By selecting a repeater structure that uses a different frequencyfor the repeater-to-base station link (ƒ₂) than the repeater-to-remotestation link (ƒ₁), the embedded WCD could operate at the secondfrequency, ƒ₂, while the power control commands for the WCD would causeboth the ƒ₁ and ƒ₂ gain stages to change their respective gains tosatisfy power control. Alternatively, the power control adjustment canbe configured so that the WCD provides all the gain control usingsignals only at ƒ₁, or at ƒ₂, or some combination of the twofrequencies.

[0199] In a different embodiment, if the communication system uses morethan one frequency for capacity or loading, then the repeater may bewideband in nature, and pass the multiple frequency signals from thebase station to the remote stations, and receive the multiplefrequencies (channels) from the remote units and send these back to thebase station. In this configuration, the power control commands for theWCD in the repeater may come from one of the channels, and that channelcause the gain for all channels to change in a similar fashion, or theWCD could enter a call on different channels and process the powercontrol commands on these channels and cause the gain for all thechannels to change in a similar fashion, or the WCD could enter a callon different channels and cause the gain to change for only thatchannel.

[0200] XIII. Multiple Repeaters

[0201] Another manner in which the present invention can advantageouslyextend the reach of a communication system is through the use of morethan one repeater or a chain of repeaters which communicate through eachother. That is, one repeater is in communication or establishescommunication links with a base station, but additional repeatersestablish communication links with the first repeater, much like remotestations would. FIG. 9 illustrates a configuration for a communicationsystem in which multiple repeaters are used that communication amongeach other.

[0202] As shown in FIG. 9, this concept can be extended such that onerepeater can service one or more repeaters to address a broader area ofcoverage outside of the reach of a base station or having an unusualshape requiring additional resources. This is shown as repeater 902 witha service area 910 communicating with one or more of repeaters 904, 906and 908, each having service areas 914, 916, 918, respectively, toprovide a more complex shaped coverage area or large are of coverage.

[0203] Alternatively, a series of repeaters can be used in an “in aline” or linear fashion, each communicating with the next to extendcoverage over a longer distance, but potentially narrowly confined,relatively speaking, in one dimension (width). This is shown in FIG. 9as repeater 902 communicating with repeater 906, which in turncommunicates through its service area 916 with repeater 920, whichcommunicates with repeater 922 in service area 930, which uses servicearea 932 to communicate with repeater 924, and so forth. This lattertechnique can be used to more affectively address needs around longnarrow transportation corridors for instance where communication traffictends to be concentrated, at least during certain peak periods, or inremote or rural areas, without trying to cover lower usage areas nearby.

[0204] However, as shown by repeater 926 and service area 934, the lineof repeaters can “broaden” out again, as desired, by servicing two ormore repeaters at a time, rather than just one along the line.Alternatively, another line of repeaters can branch off in anotherdirection, as it were. Therefore, once an area for which coverage is notdesired or is very difficult or not possible to achieve is cleared, theservice area coverage expands or is redirected.

[0205] It could also be used to link two base stations that are spacedsome distance apart, by allowing the last repeater in the chain tocommunicate with that base station, and transfer some control or timinginformation between them while the repeaters are also addressingcommunication needs adjacent to where they are located. It is alsopossible to combine this with the multiple frequency allocation schemediscussed above to alter the frequencies at one or more points along therepeater chain, or area, to meet other interference needs or patternsencountered, or as desired. The communication signals intended forremote stations can have their respective signals generated or operatedat one frequency while the embedded WCDs can use signals operating at asecond frequency, or even a third, fourth, and so on, depending on howmany repeaters are used.

[0206] In any case, it should be understood that for these multiplerepeater configurations, embodiments of the invention allow eachrepeater to be a power-controlled repeater or not, as desired. Thepower-controlled repeaters take advantage of an embedded WCD and thesignals being transferred from one repeater to the next to adjust poweras discussed above.

[0207] XIV. Conclusion

[0208] The previous description of the embodiments above is provided toenable a person skilled in the art to make or use the present invention.While the invention has been particularly shown and described withreference to embodiments thereof, it will be understood by those skilledin the art that various changes in form and details may be made thereinwithout departing from the spirit and scope of the invention.

[0209] The present invention has been described above with the aid offunctional building blocks illustrating the performance of specifiedfunctions and relationships thereof. The boundaries of these functionalbuilding blocks have been arbitrarily defined herein for the convenienceof the description. Alternate boundaries can be defined so long as thespecified functions and relationships thereof are appropriatelyperformed. Any such alternate boundaries are thus within the scope andspirit of the claimed invention. One skilled in the art will recognizethat these functional building blocks can be implemented by discretecomponents, application specific integrated circuits, processorsexecuting appropriate software and the like or many combinationsthereof. Thus, the breadth and scope of the present invention should notbe limited by any of the above-described exemplary embodiments, butshould be defined only in accordance with the following claims and theirequivalents.

What we claim as our invention is:
 1. A method of controlling outputpower for a repeater communicating with one or more base stations in awireless communication system, comprising: coupling a pre-selectedportion of a donor base station communication signal intended for remotestations to an embedded wireless communication device within saidrepeater; establishing a reverse communication link between saidwireless communication device and said donor base station in response tosaid pre-selected portion using a reverse link signal path substantiallyin common with remote station communication signals being transferred tosaid base station; and receiving power adjustment information for saidwireless communication device from said donor base station andgenerating at least one power control signal for adjusting the returnlink gain of said repeater.
 2. The method of claim 1 wherein adjustingthe return link gain of said repeater comprises: receiving poweradjustment information for said wireless communication device from saiddonor base station; generating at least one power control signal foradjusting the output transmission power of said wireless communicationdevice; and adjusting the return link gain of said repeater based onsaid power control signal.
 3. The method of claim 2 further comprisinggenerating an automatic gain control signal in said wirelesscommunication device as said at least one power control signal.
 4. Themethod of claim 1 further comprising: receiving a communication signalfrom said donor base station to be transferred to remote stations;receiving communication signals from one or more remote stations to betransferred to said base station along a predetermined signal path;processing said pre-selected portion in said wireless communicationdevice to establish a forward communication link; generating a reverselink communication signal in said wireless communication device for saiddonor base station; transferring said reverse link communication signalfrom said wireless communication device along with said signals receivedfrom said covered remote stations along a predetermined reverse link incommon with remote station communication signals to said donor basestation; receiving a directed communication signal from said donor basestation for said wireless communication device and generating said powercontrol signal; detecting said power control signal by said repeater;and adjusting said return link gain based on said detected power controlsignal.
 5. The method of claim 1 further comprising: amplifyingcommunication signals received from said donor base station;transmitting amplified donor signals to at least one remote station;amplifying communication signals received from one ore more remotestations; transmitting amplified cover signals to said base station;transferring amplified covered remote communication signals and receiveddonor base station communication signals through a duplexer; andtransferring amplified donor base station communication signals andreceived remote station communication signals through a duplexer.
 6. Themethod of claim 5 further comprising attenuating said pre-selectedportion of a donor base station communication signal before transfer tosaid wireless communication device by a pre-selected amount; attenuatingsaid return link signal output by said wireless communication device;and combining a resulting attenuated return link signal from saidwireless communication device with remote station communication signals.7. The method of claim 1 further comprising: receiving a communicationsignal from said donor base station having a first frequency; andreceiving communication signals from one or more remote stations havinga second frequency different from said first.
 8. The method of claim 7further comprising: establishing a forward communication link betweensaid wireless communication device and said donor base station usingsaid first frequency; and establishing a reverse communication linkbetween said wireless communication device and said donor base stationusing said second frequency.
 9. The method of claim 7 further comprisingadjusting the repeater gain for said second frequency based on poweradjustment information for said first frequency.
 10. The method of claim7 further comprising adjusting the repeater gain for said secondfrequency based on power adjustment information for both said first andsecond frequencies.
 11. The method of claim 1 further comprisingproducing said communication signals using a standard selected from thegroup of CDMA, WCDMA, TDMA, TD-SCDMA, and GSM.
 12. The method of claim 1further comprising periodically establishing a communication linkbetween said wireless communication device and said donor base stationand receiving power adjustment information for said wirelesscommunication device from said donor base station and calibrating a gainset point for said repeater.
 13. Apparatus for controlling output powerfor a repeater communicating with one or more donor base stations in awireless communication system, comprising: means for coupling apre-selected portion of a donor base station communication signalintended for remote stations to an embedded wireless communicationdevice within said repeater; means for establishing a communication linkbetween said wireless communication device and said donor base stationin response to said pre-selected portion using a reverse link signalpath substantially in common with remote station communication signals;and means for receiving power adjustment information for said wirelesscommunication device from said donor base station and for generating atleast one power control signal for adjusting the return link gain ofsaid repeater.
 14. The apparatus of claim 13 wherein said means forreceiving and adjusting comprises: means for receiving power adjustmentinformation for said wireless communication device from said donor basestation; means for generating at least one power control signal foradjusting the output transmission power of said wireless communicationdevice; and means for adjusting the return link gain of said repeaterbased on said power control signal.
 15. The method of claim 14 furthercomprising means for generating an automatic gain control signal in saidwireless communication device as said at least one power control signal.16. The apparatus of claim 13 further comprising: means for receiving acommunication signal from said donor base station to be transferred toremote stations; means for receiving communication signals from one ormore remote stations to be transferred to said base station along apredetermined signal path; means for processing said pre-selectedportion in said wireless communication device to establish a forwardcommunication link; means for generating a reverse link communicationsignal in said wireless communication device for said donor basestation; means for transferring said reverse link communication signalfrom said wireless communication device along with said signals receivedfrom said covered remote stations along said predetermined signal pathto said donor base station; means for receiving a directed communicationsignal from said donor base station for said wireless communicationdevice and generating said power control signal; means for detectingsaid power control signal by said repeater; and means for adjusting saidreturn link gain based on said detected power control signal.
 17. Theapparatus of claim 13 further comprising: means for amplifyingcommunication signals received from said donor base station; means fortransmitting amplified donor signals to at least one remote station;means for amplifying communication signals received from one ore moreremote stations; means for transmitting amplified cover signals to saidbase station; means for transferring amplified covered remotecommunication signals and received donor base station communicationsignals through a duplexer; and means for transferring amplified donorbase station communication signals and received remote stationcommunication signals through a duplexer.
 18. The apparatus of claim 14further comprising means for attenuating said pre-selected portion of adonor base station communication signal before transfer to said wirelesscommunication device be a pre-selected amount; and means for attenuatingsaid return link signal output by said wireless communication device;and combining a resulting attenuated return link signal from saidwireless communication device with remote station communication signals.19. The apparatus of claim 13 further comprising: means for receiving acommunication signal from said donor base station having a firstfrequency; and means for receiving communication signals from one ormore remote stations having a second frequency different from saidfirst.
 20. The method of claim 19 further comprising: means forestablishing a forward communication link between said wirelesscommunication device and said donor base station using said firstfrequency; and means for establishing a reverse communication linkbetween said wireless communication device and said donor base stationusing said second frequency.
 21. The method of claim 19 furthercomprising adjusting the repeater gain for said second frequency basedon power adjustment information for said first frequency.
 22. The methodof claim 19 further comprising adjusting the repeater gain for saidsecond frequency based on power adjustment information for both saidfirst and second frequencies.
 23. The apparatus of claim 19 furthercomprising: means for transmitting amplified donor signals to at leastone remote station and for transmitting amplified remote station signalsto said base station at said first frequency; and means for transmittingreverse link signals from said wireless communication device to saiddonor base station at a second frequency.
 24. The method of claim 13further comprising means for producing said communication signals usinga standard selected from the group of CDMA, WCDMA, TDMA, TD-SCDMA, andGSM.
 25. The apparatus of claim 13, further comprising means forperiodically establishing a communication link between said wirelesscommunication device and said donor base station, and receiving poweradjustment information for said wireless communication device from saiddonor base station and calibrating a gain set point for said repeater.26. A method of controlling noise in a donor base station incommunication with a repeater communicating with the base station andone or more remote stations in a wireless communication system,comprising: transferring a pre-selected portion of a donor base stationcommunication signal intended for remote stations to an embeddedwireless communication device within said repeater; establishing acommunication link between said wireless communication device and saiddonor base station in response to said pre-selected portion bytransmitting a return link signal over a return signal path shared withremote station communication signals being transferred to said basestation; receiving power adjustment information for said wirelesscommunication device from said donor base station and generating atleast one power control signal for adjusting the output transmissionpower of said wireless communication device; and adjusting the returnlink gain of said repeater based on said power control signal. 27.Apparatus for controlling noise in a donor base station in communicationwith a repeater communicating with the base station and one or moreremote stations in a wireless communication system, comprising: meansfor transferring a pre-selected portion of a donor base stationcommunication signal intended for remote stations to an embeddedwireless communication device within said repeater; means forestablishing a communication link between said wireless communicationdevice and said donor base station in response to said pre-selectedportion by transmitting a return link signal over a return signal pathshared with remote station communication signals being transferred tosaid base station; means for receiving power adjustment information forsaid wireless communication device from said donor base station andgenerating at least one power control signal for adjusting the outputtransmission power of said wireless communication device; and means foradjusting the return link gain of said repeater based on said powercontrol signal.
 28. A power-controlled repeater communicating with oneor more donor base stations and remote stations in a wirelesscommunication system, comprising: first circuitry for processingcommunication signals received from said donor base station for transferto remote stations; second circuitry for processing communicationsignals received from said remote stations for transfer to a donor basestation; a wireless communication device connected to said first andsecond circuitry so as to receive at least a pre-selected portion ofcommunication signals received from said donor base station and toestablish a communication link with said donor base station in responseto said pre-selected portion over a return signal path in common withremote station communication signals being transferred to said basestation, the wireless device being further connected to adjust thereturn link gain of said repeater based on power changes made inresponse to characteristics of the established communication link. 29.The repeater of claim 28, wherein said first and second circuitry areconfigured to: amplify and transmit donor signals to at least one remotestation and amplify and transmit remote station signals to said donorbase station at a first frequency; and amplify and transmit reverse linksignals from said wireless communication device to said donor basestation at a second frequency.
 30. The repeater of claim 29 furthercomprising means for adjusting the repeater gain for said secondfrequency based on power adjustment information for said firstfrequency.
 31. The repeater of claim 29 further comprising means foradjusting the repeater gain for said second frequency based on poweradjustment information for both said first and second frequencies. 32.The repeater of claim 29 further comprising: means for transmittingamplified donor signals to at least one remote station and fortransmitting amplified remote station signals to said base station atsaid first frequency; and means for transmitting reverse link signalsfrom said wireless communication device to said donor base station at asecond frequency.
 33. The repeater of claim 13 further comprising meansfor producing communication signals using a standard selected from thegroup of CDMA, WCDMA, TDMA, TD-SCDMA, and GSM.
 34. A method of providingsignal coverage in a communication system employing two or morerepeaters in communication with a base station while minimizing noise inthe base station produced by the presence of one or more repeaters,comprising: coupling a portion of a donor base station communicationsignal intended for remote stations to a first embedded wirelesscommunication device within a first repeater; establishing a reversecommunication link between the first wireless communication device inthe first repeater and said donor base station in response to saidportion using a return path shared with remote station communicationsignals being transferred to said base station from a second repeaterthrough the first repeater; receiving power adjustment information forsaid first wireless communication device from said donor base stationand generating at least one power control signal for adjusting theoutput transmission power of said first wireless communication device insaid first repeater; and adjusting the return link gain of said firstrepeater based on said power control signal.
 35. The method of claim 34,further comprising: transferring a second portion of a donor basestation communication signal amplified and transmitted by said firstrepeater and intended for remote stations to a second embedded wirelesscommunication device within a second repeater; establishing acommunication link between said second wireless communication device insaid second repeater and said first repeater in response to said secondpre-selected portion by transmitting a return link signal over a returnsignal path shared with remote station communication signals beingtransferred to said base station from a third repeater through thesecond repeater; receiving power adjustment information for second saidwireless communication device from said first repeater and generating atleast one power control signal for adjusting the output transmissionpower of said second wireless communication device in said second firstrepeater; and adjusting the return link gain of said second repeaterbased on said power control signal
 36. The method of claim 34 whereinsaid first and second repeaters are configured to: amplify and transmitdonor signals to at least one remote station and amplify and transmitremote station signals to said donor base station at a first frequency;and amplify and transmit reverse link signals from said first and secondwireless communication devices at a second frequency.
 37. The method ofclaim 34 wherein said addition repeaters are configured to: amplify andtransmit donor signals to at least one remote station and amplify andtransmit remote station signals to said donor base station at a onefrequency; and amplify and transmit reverse link signals from embeddedwireless communication devices at another frequency.
 38. A repeatercomprising: RF circuitry for processing communication signals; a phoneembedded in the repeater and coupled to said RF circuitry; and means forusing closed loop power control functions of said phone to adjusttransmission power levels used by said repeater; whereby gain variationand operating point are stabilized as the said phone corrects transmitpower under commands from closed loop power control processing.
 39. Therepeater of claim 38 wherein communication signals being processed bysaid repeater are CDMA type spread spectrum modulated communicationsignals.
 40. A repeater of comprising: a first duplexer having an outputconnected to a receive chain and an input connected to a transmit chain;said receive chain comprising a coupler with an input connected to theoutput of said first duplexer and two outputs, one of which is connectedin series with a first set of one or more amplifiers; a first fixedattenuator connected in series with said first amplifiers; a secondduplexer having an input connected to receive an output from said firstamplifiers; a combiner having two inputs and one output with one inputconnected to receive an output from said second duplexer; one or moreamplifiers connected in series with an output of said combiner; a secondfixed attenuator connected in series with said amplifiers; a digitalstep attenuator connected in series with an output of said secondattenuator having an output coupled to said first duplexer input and acontrol input; a circulator having a receiver input connected to anoutput of said coupler and a transmission output connected to the secondinput of said combiner, and an antenna input; a third fixed attenuatorconnected in series with said circulator receiver input; a fourth fixedattenuator connected in series with said transmission output of saidcirculator and the second input of said combiner; a repeater phonehaving an antenna output connected to said antenna input of saidcirculator, and at least a gain control output, a call notificationoutput, and a pick-up/hang-up output; and a micro-controller connectedwith an output to said digital step attenuator control input for issuingcommands to control the attenuation and power output thereby, and atleast a gain control input, a call notification input, and apick-up/hang-up input each being connected to corresponding outputs forsaid repeater phone.
 41. The repeater of claim 40 wherein communicationsignals being processed by said repeater use a standard selected fromthe group of CDMA, WCDMA, TDMA, TD-SCDMA, and GSM.
 42. A wirelesscommunication system comprising: one or more donor base stations; one ormore remote stations; and a power controlled repeater communicating withsaid base station and one or more remote stations, comprising: means forcoupling a portion of a base station communication signal to an embeddedwireless communication device within said repeater; means forestablishing a reverse link between said wireless communication deviceand a donor base station using a return link signal over a return signalpath common with remote station communication signals; and means forreceiving power adjustment commands from said donor base station andgenerating at least one power control signal for adjusting outputtransmission power.